1. Field of the Invention
The present invention relates to a vehicular interior part and a manufacturing method thereof.
2. Description of the Related Art
According to an conventional art related to a vehicular interior part, for instance, in Japanese Patent Application Publication No. JP-A-2002-79852 (pages 3-4 and FIG. 2), a cover comprising a plurality of skin materials joined together is covered on a surface of a plastic base material. The cover according to the conventional art is structured as follows: a pair of skin materials is overlapped with their right sides of the skin together, then is sewn together with respective edges thereof aligned, and thereafter, each of the pair of the skin materials is spread in the opposite direction from each other. Accordingly, a certain width of a seam allowance protrudes toward the backside from a stitch portion of the cover. As a consequence, when the cover is covered over the surface of the base material, there is a disadvantage that the seam allowance protrudes from the surface of the base material and creating a bulge on the surface of a vehicular interior part. To solve the problem, the vehicular interior part according to the conventional art has a concave portion provided on the surface of the base material to accommodate the seam allowance. This structure thus prevents formation of the bulge on the surface of the vehicular interior part caused by the seam allowance of the cover. Accordingly, the vehicular interior part according to the conventional art has an advantage that the seam allowance of the cover does not protrude from the surface, thereby allowing the surface to be smooth and have a good appearance.
However, the vehicular interior part according to the conventional art must be provided with the concave portion on the surface of the base material to accommodate the seam allowance of the cover. Therefore, a forming die to form the base material becomes complicated. As a result, the cost for manufacturing the base material becomes high and, in some cases, it may be difficult to perform die cutting of the base material during the forming process.
On the other hand, according to other conventional art, there exists a vehicular interior part in which a cover is formed by attaching a cushion material to a backside of a skin material while avoiding a seam allowance of a stitch portion, and then the cover is adhered to a surface of a base material. In the case in which the cover is attached to the surface of the base material, intervention of the cushion material prevents the seam allowance from protruding from the surface of the base material. Accordingly, without requiring the surface of the base material to be provided with a concave portion to accommodate the seam allowance, this structure can prevent formation of a bulge on the surface of the vehicular interior part and can also allow the surface of the vehicular interior part to be flat and have a good appearance.
According to the vehicular interior part of the conventional art, the cushion material is attached to the backside of the skin material before simultaneously forming the skin material and the cushion material into a certain shape in accordance with a surface shape of the base material. Therefore, a stress is caused on the cushion material due to factors such as a difference in the elongation of the skin material and the cushion material. This stress then creates problems such as formation of a crease on the skin material, which significantly degrades the appearance of the surface of the vehicular interior part.
The present invention has been made in consideration of the aforementioned circumstances, and it is an object of the present invention to provide a vehicular interior part with a good appearance and a manufacturing method thereof.